News and CommentaryOrigins & Design 17:1

Colin Patterson Revisits His Famous
Question about Evolution

Paul A. Nelson

Authoritative," conveying "an impression of moody
rebelliousness," and "habitually pessimistic"--thus
writer Tom Bethell described the paleontologist and systematist
Colin Patterson, on first meeting him in 1983.1

Patterson, who works at the British Museum of Natural History
in London, is one of the leaders of the philosophy of biological
systematics known as "transformed cladistics." The public
hubbub which surrounded "transformed" or "pattern"
cladistics in the 1980s has now generally subsided, although the
issues lying at the heart of the controversy have not. Indeed,
Patterson has revisited those issues, which were captured in large
measure by a famous question he first posed nearly fifteen years
ago. "Can you tell me anything about evolution," he
asked his listeners, "any one thing, that is true?"

On November 5, 1981, Patterson gave a now infamous talk at
the American Museum of Natural History in New York, to the Systematics
Discussion Group which met monthly at the museum. An unknown creationist
in the audience secretly taped the talk, and a transcript was
soon circulating as samizdat among creationists, and shortly
thereafter among the scientific community at large.

The uncorrected transcript was plainly flawed--giving "Conbear"
for "von Baer," for instance, and omitting the names
of well-known biologists--but enough of Patterson's provocative
points came through to ignite the firestorm which followed. Patterson
soon came in for heavy criticism from the evolutionary community.
The talk was much debated: what had he meant; was he simply tweaking
noses in New York; what did he really think about evolution?

As creationist writers trumpeted the speech, Patterson retreated,
understandably annoyed by the episode and the voluminous correspondence
he received in its wake.

In August 1993, at a Systematics Association meeting in London,
Patterson revisited his 1981 talk; specifically, the bearing of
evolution on the practice and philosophy of systematics: ordering
the relationships of organisms. In his recollections (published
last year; see the notes on p.7), Patterson describes the background
to the talk:

In November 1981, after an invitation from Donn Rosen [a fish
systematist at the American Museum, now deceased], I gave a talk
to the Systematics Discussion Group in the American Museum of
Natural History. Donn asked me to talk on 'Evolutionism and Creationism',
and it happened that just one week before my talk Ernst Mayr
published a paper on systematics in Science (Mayr 1981).
Mayr pointed out the deficiencies (in his view) of cladistics
and phenetics, and noted that the 'connection with evolutionary
principles is exceedingly tenuous in many recent cladistic writings.'
For Mayr, classifications should incorporate such things as 'inferences
on selection pressures, shifts of adaptive zones, evolutionary
rates, and rates of evolutionary divergence.' Fired up by Mayr's
paper, I gave a fairly radical talk in New York, comparing the
effect of evolutionary theory on systematics with Gillespie's
(1979, p. 8) characterization of pre-Darwinian creationism: 'not
a research govering theory (since its power to explain was only
verbal) but an antitheory, a void that had the function of knowledge
but, as naturalists increasingly came to feel, conveyed none.'
Unfortunately, and unknown to me, there was a creationist in
my audience with a hidden tape recorder. A transcript of my talk
was produced and circulated among creationists, and the talk
has since been widely, and often inaccurately, quoted in creationist
literature. 2

But despite the inaccuracies, Patterson's central question
about evolution came through unmistakably:

But one sentence from the talk was accurately reproduced,
and was perhaps quoted more than any other. The sentence was
a rhetorical question; I quote it from a creationist source (Johnson
1991, p.10): 'Can you tell me anything about evolution, any one
thing that is true?'3

The question still matters, Patterson argues, because evolution
is still assumed to be the primary determinant of phylogenetic
reasoning. But Patterson's agnosticism about evolution--expressed
in 1981 as, "I had been working on this stuff for twenty
years, and there was not one thing I knew about it"--continues
today.

Patterson describes that agnosticism by looking at patterns
in molecular data.

At first, he notes, he thought he had found answers to his
own question:

In 1981, I knew of no sensible answer to the question, but
in the ensuing decade I came to believe that there were two things
I knew about evolution. First, that transitions [purines, adenine
(A) and guanine (G), mutating to purines, e.g., A --> G; or
pyrimidines, cytosine (C) and thymine (T), mutating to pyrimidines,
e.g., T --> C] are more frequently fixed than transversions
[where a purine mutates to a pyrimidine, or vice versa] and second,
that at the level of DNA, the great majority of substitutions
take place despite natural selection rather than because of it.
4

However, as Patterson continues, he came to doubt whether in
seeing these patterns he was grasping the process of evolution:

...do transition bias and neutral substitution represent knowledge
about evolution, or something else? Further, and more generally,
why should I, a morphologist, claim to know something about molecular
evolution but nothing of morphological evolution? 5

We must distinguish between patterns to be explained, Patterson
urges, and the process theories by which we explain those patterns--a
distinction foundational to the "transformed cladistic"
perspective on systematics and phylogeny. The molecular patterns
he observed, Patterson believes, are thus only data awaiting explanation.

"I therefore believe I was mistaken in thinking that
I knew something about molecular evolution," he writes.
"Instead, I know (or have learned) something about the properties
of molecular data, and those properties are amongst the things
that must be explained by evolutionary theory."

Patterson concludes:

...I mentioned a question ('Can you tell me anything you know
about evolution?') that I have put to various biologists, and
an answer that had been given: 'I know that evolution generates
hierarchy.' In the framework of phylogenetic reconstruction and
our current problems with it, another answer comes to mind: 'I
know that evolution generates homoplasy' [or "convergence,"
in the older jargon of systematics]. In both cases, the answer
is not quite accurate. It would be truer to say, 'I know that
evolution explains hierarchy' or 'I know that evolution
explains homoplasy.' We must remember the distinction
between the cart--the explanation--and the horse--the data. And
where models are introduced in phylogenetic reconstruction, we
should prefer models dictated by features of the data to models
derived from explanatory theories. 6

Among the issues raised by Patterson's revisiting of his 1981
question, probably the most significant is how do we know which
patterns are real (and therefore, actually need explaining)?
"Transition bias is data," he argues--but only if one
assumes the common descent of the gene sequences in question,
meaning, in most cases, macroevolution. For some design theorists,
who doubt that macroevolution is possible, sequence comparisons
between divergent animal phyla (for instance) will not
be data showing a historical relationship from an unknown common
ancestor--a relationship requiring causal explanation. Rather,
those data may reflect any number of causes other than descent.

Data--"facts" requiring explanation--emerge against
a background of causal possibility. Because they are highly skeptical
of the possibility of macroevolution, some design theorists would
deny that the systematic hierarchy is real, in the same
sense that the branching pattern of an elm tree or the Hapsburg
Dynasty is real, i.e., something extending through space
and time.

Thus, they would seek a nominalist explanation for the systematic
hierarchy (reflecting, perhaps, our desire to organize data in
bifurcating trees), and would defend that by arguing that the
transformations required by macroevolution are probabilistically
inaccessible. (Other design theorists would accept the hierarchy
as actual, of course, a genuine tree of life, but would argue
that the tree exists only because of a designer's intervention
to make the necessary transitions between forms possible.)

The real crunch between Patterson and design theorists, however,
arises from the possibility of design. The presence of cytochrome
c in, say, echinoderms, and the same protein in humans, gives
evolutionists an historical linkage between the two forms, even
in the absence of a theory of macroevolution, simply because high
degrees of molecular similarity require a common cause.

For most methodological naturalists, that can only be descent
with modification. 7

But suppose, as seems possible, that a designer employed the
same cytochrome molecule in two distinct lineages (echinoderms
and humans)? The usual naturalist response holds while this is
certainly possible, any theory making such predictions is empty.
Assertions about the designer's actions are unconstrained, and
would fit whatever data turn up.

But that does not follow. A designer who is free to employ
the same molecules in constructing diverse organisms is not therefore
an agent who acts capriciously. Furthermore, a design theorist
would locate the empirical content of his theory elsewhere, in
those predictions which distinguish design from naturalistic descent.
It is the whole case for design, taken broadly, that gives the
theory empirical content. 8

But the step to the possibility of design, it seems, is a far
longer stride than the shorter step from certainty to agnosticism
about evolution. One hopes, in any case, that Patterson will join
the debate, wherever he ends up standing.

7. Patterson, for
instance, argues: "Convergence between molecular sequences
is too improbable to occur, just as similarity between sequences
is improbable to be explained except by common ancestry. Some
might view this argument as viciously or vacuously circular,
but the same argument is routinely advocated in morphology....This
is the argument from complexity: if two structures are complex
enough and similar in detail, probability dictates that they
must be homologous rather than convergent." See C. Patterson,
"Homology in Classical and Molecular Biology," Molecular
Biology and Evolution 5 (1988): 603-625; p. 615. This argument,
as with all arguments assuming naturalism, excludes intelligent
causation, which may yield independent similarities in the absence
of any material descent. Doubtless all instances of Colin Patterson's
handwritten signature, for example--on documents from bank checks
to personal letters--are spatiotemporally distinct (i.e., not
"descended" from other signatures), yet the signatures
themselves will be remarkably similar, having, as they do, a
unitary cause in Colin Patterson himself.

8. Stephen C. Meyer,
"The Methodological Equivalence of Design and Descent: Can
There Be A Scientific Theory of Creation?" in The Creation
Hypothesis, ed. J.P. Moreland (Downer's Grove, Illinois:
InterVarsity Press, 1994), pp.67-112.